The Institute of Electrical and Electronics Engineers (IEEE) is amending Ethernet standards to equip Ethernet with new features required for Wide Area Network (WAN) deployment. The relevant extensions include: Connectivity Fault Management (CFM); Provider Bridging (PB); Provider Backbone Bridging (PBB); and Provider Backbone Bridging-Traffic Engineering (PBB-TE).
PB and PBB are enhancing Ethernet scalability. With PB, a new Virtual Local Area Network (VLAN) tag, the Service VLAN (S-VALN) tag, has been introduced to allow providers to use a separate VLAN space while transparently maintaining the Customer VLAN (C-VLAN) information.
PBB allows a full separation of the customer and provider address spaces by encapsulating customer frames adding a “backbone” MAC header. This enables both the MAC addresses and the whole VLAN space to be in control of the provider. The fields of the encapsulation header for the “Backbone” MAC header include Backbone Destination Address (B-DA), Backbone Source Address (B-SA) and Backbone VLAN (B-VLAN). In addition to the “backbone” MAC header, a new tag, the Service Instance Tag (I-TAG) is added when customer frames are encapsulated. The I-TAG has a 24-bit Service Instance Identifier (I-SID) field. The I-SID unambiguously identifies customer services. In PBB, edge bridges, such as Backbone Edge Bridges (BEBs), which process customer frames and add the backbone MAC header, and the I-SID can be distinguished from core bridges, such as Backbone Core Bridges (BCBs), which are forwarding frames based on the backbone MAC header.
PBB-TE decouples the Ethernet data and control planes by explicitly supporting external control/management mechanisms to configure static filtering entries in bridges and creating explicitly routed connections. In addition, PBB-TE defines mechanisms for 1:1 protection switching of bidirectional Ethernet connections.
In the Internet Engineering Task Force (IETF), the Generalized Multiprotocol Label Switching (GMPLS) controlled Ethernet Label Switching (GELS) is extending the GMPLS control plane for PBB-TE Ethernet networks. GMPLS established PBB-TE connections are referred to as Ethernet Label Switched Paths (LSPs). GELS enables the application of Multiprotocol Label Switching-Traffic Engineering (MPLS-TE) and GMPLS provisioning and recovery features in Ethernet networks.
In PBB, the I-SID identifies a service instance. However, there is currently no mechanism in GMPLS to provide this information.